In connection with the fabrication or manufacture of threaded fasteners, a multiplicity of different threaded fasteners are of course well-known in the industry and are accordingly available in the marketplace. More particularly, or furthermore, the multiplicity or different varieties of threaded fasteners have been developed in accordance with various objectives, such as, for example, to enable the different threaded fasteners to achieve predeterminedly desired insertion and withdrawal torque characteristics, to enable the different threaded fasteners to be respectively used in conjunction with different mounting panels, support surfaces, or substrates comprising different types of materials, to enable the threaded fasteners to exhibit predeterminedly desired pull-out resistance values with respect to such panels, support surfaces, or substrates, and the like. Accordingly, the threads of such threaded fasteners are usually provided with supplemental or auxiliary structures which enable or facilitate the achievement of the aforenoted objectives. Threaded fasteners of the foregoing types, for achieving the aforenoted objectives, are disclosed, for example, within U.S. Pat. No. 6,254,327 which issued to Chen on Jul. 3, 2001, U.S. Pat. No. 6,152,666 which issued to Walther et al. on Nov. 28, 2000, U.S. Pat. No. 6,086,302 which issued to Gerhard on Jul. 11, 2000, U.S. Pat. No. 6,056,491 which issued to Hsu on May 2, 2000, U.S. Pat. No. 5,897,280 which issued to Dicke on Apr. 27, 1999, U.S. Pat. No. 5,827,030 which issued to Dicke on Oct. 27, 1998, U.S. Pat. No. 5,110,245 which issued to Hiroyuki on May 5, 1992, U.S. Pat. No. 5,044,853 which issued to Dicke on Sep. 3, 1991, U.S. Pat. No. 4,842,467 which issued to Armstrong on Jun. 27, 1989, U.S. Pat. No. 4,637,767 which issued to Yaotani et al. on Jan. 20, 1987, and U.S. Pat. No. 3,083,609 which issued to Lovisek on Apr. 2, 1963.
It is seen, for example, as disclosed within the aforenoted patent issued to Chen, that the PRIOR ART screw or fastener, as illustrated in FIG. 1, comprises a shank portion 1 having a plurality of spiral circular threads 11 formed thereon, wherein the plurality of spiral circular threads 11, disposed upon the lower portion of the shank 1, has a plurality of pointed teeth 12 disposed thereon. Alternatively, the improved screw or threaded fastener 2, as disclosed within FIG. 2, comprises a plurality of spiral circular threads 21 disposed upon the upper portion of the screw or threaded fastener 2, while a plurality of spiral triangular threads 22, each comprising three pointed tips 221 angularly displaced with respect to the three pointed tips 221 disposed upon adjacent ones of the threads 22, are disposed upon the lower portion of the screw or threaded fastener 2. It is noted however that these different structural features enable this particular threaded fastener to only be uniquely useful in connection with the insertion of the fastener within hard wood.
Continuing further, as disclosed within the aforenoted patent issued to Walther et al., there is disclosed a screw, as illustrated within FIGS. 1 and 2, which comprises a shank portion 10 upon which there is disposed a helical thread 15. In particular, intermediate threads 17 of the helical thread 15 are provided with a plurality of cutouts 19,20,21, wherein each one of cutouts 19,20,21 comprises a pair of V-shaped cutout sections 22,23 whereby, as a result of the combination of the adjacent pair of V-shaped cutout sections 22,23, each one of the cutouts 19,20,21 has a substantially W-shaped configuration comprising a central tooth 24. It is also noted, howver, that the plurality of cutouts 19,20,21 are respectively separated from each other through means of an angular displacement of approximately 120°, and as a result of such aforenoted composite structure, it is noted further that this screw fastener is particularly or uniquely adapted only for use within fibrous materials, such as, for example, wood. In a similar manner, as disclosed within the aforenoted patent issued to Gerhard, there is likewise disclosed a screw, as illustrated within FIGS. 1 and 5, which comprises a core 1 having a helical thread 5 formed upon the external portion of the core 1. A plurality of cutting notches 10 are formed within the outer peripheral surface 8 of the thread 5, and it is seen that each one of the cutting notches 10 has a substantially V-shaped configuration as defined by means of oppositely cooperating edges 13,15. As can best be appreciated from FIG. 4, however, it is also seen that the helical thread 5 comprises a large acme thread wherein the opposite side surfaces of the helical thread 5 are disposed parallel to each other, at 90° or perpendicular to the longitudinal axis of the core 1 whereby the flank angle is 0°. It is noted that this particular screw, having the particular thread structure incorporated thereon, has been specifically designed for use only in connection with self-tapping operations to be performed within concrete, brick, or similar masonry. In addition, it is also noted that in order to viably achieve such self-tapping operations, the screw must be driven into the concrete, brick, or masonry by means of a commercial or industrial impact tool.
Continuing yet still further, as disclosed within the aforenoted patent to Hsu, a screw comprises structure which, again, renders the same uniquely adapted only for use in connection with carpentry, that is, for insertion within wood workpieces. It is specifically noted, for example, that a PRIOR ART screw, as illustrated within FIG. 6 and comprising a tapered portion 11 and a constant-diameter shank portion 12, tended to crack the wood workpieces because the screw was simply forced into the wood workpieces without initially cutting off bits of the wood workpieces. In order to therefore effectively prevent the cracking of the wood workpieces, the PRIOR ART screw as disclosed within FIG. 7 was developed, whereby a cutting recessed surface 14 was provided in conjunction with the tapered portion 11 so as to initially cut a hole within the wood workpiece. It was noted, however, that such a screw was not able to be manufactured in a viable manner, and in addition, the screw was effectively unbalanced due to the fact that the recessed surface 14 was formed upon only one half of the screw. Accordingly, the screw 2, as disclosed within FIGS. 1-5, was developed wherein a cutting thread 22, comprising a plurality of cutting teeth 23, is provided upon the leading end portion of the screw. It is noted, however, that the cutting teeth 23 comprise pointed teeth structures, and that they are disposed at a positive rake angle, that is, they face, or are disposed toward, the screw-in direction. Accordingly, such structural features render the screw 2 uniquely adaptable for easy insertion into wood workpieces as a result of the fact that this screw 2 interacts with the wood workpiece or substrate in a cutting manner, as opposed to an abrading manner. Additionally, in conjunction with the aforenoted structure, the screw 2 is also preferably provided with guide projections 26 so as to facilitate the discharge or dispersal of the wood bits as the same are cut from the wood workpiece.
Additional examples of PRIOR ART screw fasteners are disclosed within the three aforenoted patents which issued to Dicke, and it is again noted, in connection with each one of the screw fasteners as disclosed within such patents, that the screw fasteners are specifically designed so as to facilitate the insertion of the same into wood substrates. More particularly, the peripheral edge portions of at least some of the threads formed upon the screw fastener are provided with undulations or indentations comprising wave peaks or crests and wave valleys or troughs, and wherein further, such undulation or indentation structure comprises skewed parabolic recesses incorporated therein. The objective of providing such undulations or indentations, and the recesses thereof, is to effectively reduce the fastener insertion moment or torque while correspondingly increasing the fastener withdrawal moment or torque. It is additionally noted, as disclosed within the aforenoted patent which issued to Hiroyuki, and as best seen in FIGS. 1 and 2, that the peripheral edge or crest portions of the threads 4 of the threaded fasteners 1 are provided with slot recesses 6 which effectively provide the fasteners 1 with enhanced stability within those substrates which are fabricated from thermoplastic resin materials. More particularly, as a result of such structure incorporated within the threads of the fastener 1, the fasteners 1 are able to be easily driven into the substrates but are effectively prevented from becoming loosened from the substrates. In a similar manner, it is noted that in accordance with the teachings of the patent which issued to Armstrong, and as can best be seen in FIG. 2 and 4, a screw fastener 10 is provided with a thread 16 wherein the crest portions thereof are provided with a plurality of V-shaped notches 20 which are circumferentially spaced apart through an angular displacement of 120° so as to specifically facilitate the cutting of hard concrete aggregate substrates.
Still further, in a somewhat reverse manner, and as disclosed within the aforenoted patent which issued to Yaotani et al., particularly FIG. 2 thereof, the threads of the fastener are provided with projections 150, as opposed to the recesses as disclosed within the aforenoted patents to Hiroyuki, Walther et al., and Armstrong, so as to optimize the torque insertion levels, as well as the pull-out resistance or retention values, characteristic of the fasteners. It is also noted that the particular fastener of Yaotani et al. is specifically designed for use in connection with substrates fabricated from suitable plastic materials. Lastly, it is noted that self-tapping screw fasteners 10 are disclosed within the aforenoted patent which issued to Lovisek, wherein, for example, as can best be seen in FIG. 1, axially extending flutes 13 are provided upon the leading end portion of the screw. It is noted, however, that the threads of the disclosed screw fastener are not provided with a circumferential array of teeth which also have predetermined flank angles. Accordingly, while the screw fasteners as disclosed within Lovisek are stated to be capable of use within different materials or substrates, such as, for example, wood, plastic, and the like, such materials are necessarily deformable and cuttable, or considered from an alternative point of view, the disclosed fasteners are not capable of being used, for example, within hard concrete aggregate or the like.
It is therefore to be appreciated that while the aforenoted exemplary threaded fasteners comprise structure which enables them to perform satisfactorily in connection with their specifically noted uses, that is, within the specifically noted substrates, a need still exists in the art for a new and improved threaded fastener which will have new and improved composite structure integrally incorporated within the thread portions thereof whereby such thread portions will be capable of effectively abrading diverse types of substrates, such as, for example, wood, metal, composite materials, concrete, hard aggregate, or the like. In this manner, a single threaded fastener can in fact be utilized to mount or secure objects, articles, mounting brackets, anchors, and the like, upon diverse types of substrates. Considered from a slightly different perspective, a single threaded fastener can be utilized in connection with any one of a plurality of diverse types of substrates as opposed to necessarily choosing different threaded fasteners for respective insertion within different substrates. In addition, lead thread portions of the threaded fastener should be able to effectively facilitate the removal or dispersal of the abraded material so as to permit the following or trailing threads to easily traverse the newly formed threads which have been tapped into the substrates by means of the lead threads, and wherein, as a result of such new and improved screw fastener thread structure, the screw fastener will exhibit enhanced tapping or insertion torque characteristics, enhanced tapping and insertion speed, and improved pull-out resistance properties.